Postgresql-11 confusing situtation

Hi,

I’m using Postgresql 11.3 on Centos 7.6.18.10 server.
I have very unusual issue which I don’t know if it is OK:

I have running postgresql server with default instance:

[root(at)pgpmaster ~]# systemctl status postgresql-11
● postgresql-11.service - PostgreSQL 11 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-11.service; enabled; vendor preset: disabled)
Active: active (running) since Wed 2019-06-05 14:37:21 CEST; 49s ago
Docs: https://www.postgresql.org/docs/11/static/
Process: 3552 ExecStartPre=/usr/pgsql-11/bin/postgresql-11-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
Main PID: 3576 (postmaster)
Tasks: 9
CGroup: /system.slice/postgresql-11.service
├─3576 /usr/pgsql-11/bin/postmaster -D /var/lib/pgsql/11/data/
├─3609 postgres: logger
├─3621 postgres: checkpointer
├─3622 postgres: background writer
├─3623 postgres: walwriter
├─3624 postgres: autovacuum launcher
├─3625 postgres: archiver
├─3626 postgres: stats collector
└─3627 postgres: logical replication launcher

Jun 05 14:37:20 pgpmaster.localhost systemd[1]: Starting PostgreSQL 11 database server...
Jun 05 14:37:20 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:20.923 CEST [3576] LOG: listening on IPv4 address "0.0.0.0", port 5432
Jun 05 14:37:20 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:20.924 CEST [3576] LOG: listening on IPv6 address "::", port 5432
Jun 05 14:37:20 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:20.928 CEST [3576] LOG: listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
Jun 05 14:37:21 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:21.026 CEST [3576] LOG: listening on Unix socket "/tmp/.s.PGSQL.5432"
Jun 05 14:37:21 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:21.123 CEST [3576] LOG: redirecting log output to logging collector process
Jun 05 14:37:21 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:21.123 CEST [3576] HINT: Future log output will appear in directory "log".
Jun 05 14:37:21 pgpmaster.localhost systemd[1]: Started PostgreSQL 11 database server.

If I restart it using systemctl restart postgresql-11 command, everything is OK, but if I use commands:
# pg_ctl -D /var/lib/pgsql/11/data/ -m immediate stop
# pg_ctl -D /var/lib/pgsql/11/data/ -m immediate start

Then I get following situtation:

# systemctl status postgresql-11
● postgresql-11.service - PostgreSQL 11 database server
Loaded: loaded (/usr/lib/systemd/system/postgresql-11.service; enabled; vendor preset: disabled)
Active: inactive (dead) since Wed 2019-06-05 14:41:32 CEST; 1min 40s ago
Docs: https://www.postgresql.org/docs/11/static/
Process: 3576 ExecStart=/usr/pgsql-11/bin/postmaster -D ${PGDATA} (code=exited, status=0/SUCCESS)
Process: 3552 ExecStartPre=/usr/pgsql-11/bin/postgresql-11-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)
Main PID: 3576 (code=exited, status=0/SUCCESS)

Jun 05 14:37:20 pgpmaster.localhost systemd[1]: Starting PostgreSQL 11 database server...
Jun 05 14:37:20 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:20.923 CEST [3576] LOG: listening on IPv4 address "0.0.0.0", port 5432
Jun 05 14:37:20 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:20.924 CEST [3576] LOG: listening on IPv6 address "::", port 5432
Jun 05 14:37:20 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:20.928 CEST [3576] LOG: listening on Unix socket "/var/run/postgresql/.s.PGSQL.5432"
Jun 05 14:37:21 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:21.026 CEST [3576] LOG: listening on Unix socket "/tmp/.s.PGSQL.5432"
Jun 05 14:37:21 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:21.123 CEST [3576] LOG: redirecting log output to logging collector process
Jun 05 14:37:21 pgpmaster.localhost postmaster[3576]: 2019-06-05 14:37:21.123 CEST [3576] HINT: Future log output will appear in directory "log".
Jun 05 14:37:21 pgpmaster.localhost systemd[1]: Started PostgreSQL 11 database server.

# ps agx | grep postgre
4592 pts/0 S 0:00 /usr/pgsql-11/bin/postgres -D /var/lib/pgsql/11/data
4593 ? Ss 0:00 postgres: logger
4595 ? Ss 0:00 postgres: checkpointer
4596 ? Ss 0:00 postgres: background writer
4597 ? Ss 0:00 postgres: walwriter
4598 ? Ss 0:00 postgres: autovacuum launcher
4599 ? Ss 0:00 postgres: archiver
4600 ? Ss 0:00 postgres: stats collector
4601 ? Ss 0:00 postgres: logical replication launcher
4630 pts/0 S+ 0:00 grep --color=auto postgre

$ pg_ctl -D /var/lib/pgsql/11/data/ status
pg_ctl: server is running (PID: 4592)
/usr/pgsql-11/bin/postgres "-D" "/var/lib/pgsql/11/data"

Systemctl shows that database is dead, but it is actually running.
Can someone explain this behavioure?

Best regards!
[izum]

Domen Šetar
Computer Systems Support
IZUM – Institute of Information Science | Prešernova ulica 17 | 2000 Maribor | Slovenia
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